In order to enhance photocatalytic water splitting rates with Pt/TiO2 powder, sufficient agitation of the biphasic medium is required to switch surficial reactions to volumetric reactions. Additionally, agitation is c...In order to enhance photocatalytic water splitting rates with Pt/TiO2 powder, sufficient agitation of the biphasic medium is required to switch surficial reactions to volumetric reactions. Additionally, agitation is conducive to higher diffusion rates of the generated hydrogen and co-produced oxygen, hindering their ability to re-couple to water on Pt loaded to TiO2 powder. In order to create agitation without consuming any electricity, a novel technique utilizing Rayleigh convection was applied, and its ability to enhance photocatalytic water splitting rates was evaluated. Higher Rayleigh convective flow rates resulted in higher photocatalytic water splitting rates. Utilization of Rayleigh convection approximately doubled the photocatalytic water splitting rates, despite relatively low convective flow velocities (obtained through simple thermo-hydrodynamic simulations). The rate enhancement achieved through Rayleigh convection is a result of its ability to disperse the ultrafine Pt/TiO2 particles throughout the whole medium, leading to volumetric reactions.展开更多
The velocity distribution in Rayleigh convection caused by acetone volatilization in acetone-ethyl acetate binary system was observed in a vertical cross section of an initially quiescent liquid layer by utilizing par...The velocity distribution in Rayleigh convection caused by acetone volatilization in acetone-ethyl acetate binary system was observed in a vertical cross section of an initially quiescent liquid layer by utilizing particle image velocimetry. Obvious turbulent vortexes that were induced by Rayleigh convection appeared in the bulk liquid,and its statistic features indicated that Rayleigh convection became more intense with the increase of Ra number and ReGnumber. Mass transfer coefficient was measured and the computed enhancement factor indicated that Rayleigh convection could promote the surface renewal of the liquid phase and intensify the interfacial mass transfer significantly. A method was proposed for the prediction of mass transfer coefficient based on the measured velocity vector, and the predicted mass transfer coefficients are in reasonable agreement with the experimental results.展开更多
文摘In order to enhance photocatalytic water splitting rates with Pt/TiO2 powder, sufficient agitation of the biphasic medium is required to switch surficial reactions to volumetric reactions. Additionally, agitation is conducive to higher diffusion rates of the generated hydrogen and co-produced oxygen, hindering their ability to re-couple to water on Pt loaded to TiO2 powder. In order to create agitation without consuming any electricity, a novel technique utilizing Rayleigh convection was applied, and its ability to enhance photocatalytic water splitting rates was evaluated. Higher Rayleigh convective flow rates resulted in higher photocatalytic water splitting rates. Utilization of Rayleigh convection approximately doubled the photocatalytic water splitting rates, despite relatively low convective flow velocities (obtained through simple thermo-hydrodynamic simulations). The rate enhancement achieved through Rayleigh convection is a result of its ability to disperse the ultrafine Pt/TiO2 particles throughout the whole medium, leading to volumetric reactions.
基金Supported by the National Natural Science Foundation of China(20736005)
文摘The velocity distribution in Rayleigh convection caused by acetone volatilization in acetone-ethyl acetate binary system was observed in a vertical cross section of an initially quiescent liquid layer by utilizing particle image velocimetry. Obvious turbulent vortexes that were induced by Rayleigh convection appeared in the bulk liquid,and its statistic features indicated that Rayleigh convection became more intense with the increase of Ra number and ReGnumber. Mass transfer coefficient was measured and the computed enhancement factor indicated that Rayleigh convection could promote the surface renewal of the liquid phase and intensify the interfacial mass transfer significantly. A method was proposed for the prediction of mass transfer coefficient based on the measured velocity vector, and the predicted mass transfer coefficients are in reasonable agreement with the experimental results.
